Europe ‘Gas Bags’ Turn Dirty Problem into Clean Energy

Britain’s United Utilities Group has turned a human waste problem into a clean energy boon. When the amount of waste produced each year across the utility’s North West region reached problematic levels, it looked for a solution that wouldn’t involve dumping the waste into the Irish Sea, as had been done in the past.

The new Davyhulme sludge treatment plant in Manchester is addressing the problem, Bloomberg reports, by turning human waste into clean energy. The sludge recycling center, built by Black & Veatch for the utility, uses a process called thermal hydrolysis (THP) to improve the amount of energy produced from the sludge. The plant produces enough energy to be 96 percent energy neutral and can even export surplus power to the UK grid.

Sludge is digested to generate biogas, which is stored in two giant green “gas bags”—Europe’s largest inflatable gas holders. The biogas is then cleaned and used as fuel for five CHP engines and three steam boilers. The bags generate about 60 GWh of energy a year, according to the utility.

Enough heat is recycled from CHP engines that the plant’s steam boilers rarely need to be fired up to heat the reaction vessels, so almost all the gas produced is used for generating electricity.

United Utilities is capitalizing on its THP success with the world’s first sludge-powered data center, due to be completed at Davyhulme next month.